Vehicle seat suspensions are used to support a person sitting in a seat while also absorbing bumps and jolts encountered by the vehicle during operation to make the seat occupant's ride as comfortable as possible. While a seat suspension designer's job has always been difficult in achieving these goals, their job today is even more complicated because they are being asked to design suspensions that are more compact, lighter in weight, cheaper to build, more durable, and which offer greater comfort. Furthermore, for seat suspensions being designed for the European market, the suspension must also possess favorable natural frequency characteristics and pass strict ISO tests.
For off-road vehicle seating applications, the seat suspension must be extremely rugged while providing comfort to a seat occupant who can be subjected to rather severe operating conditions and rough terrain. Often, different people will use the equipment at different times, requiring the seat suspension to be adjustable for both the height of the seat and the weight of the seat occupant.
Suspensions which utilize scissor linkages are a common choice for off-road vehicle seat designers because they are robust, strong, durable, inexpensive and reliable. Moreover, they can be adapted to be adjustable both for changing seat height and for accommodating different seat occupant weights.
Unfortunately, for many of these suspensions, if not all of them, seat height and weight adjustment cannot be done independently of each other. More specifically, adjusting seat height changes the weight resisting characteristics of the suspension and adjusting the weight resisting characteristics of the invention changes seat height. Moreover, the two adjustment mechanisms also take up space thereby limiting how compact the suspension can be made. Additionally, since they are separate but interrelated mechanisms, the height and weight adjustment mechanisms use different components adding to the cost of the suspension.
With off-road vehicle equipment manufacturers demanding better, smaller and cheaper seat suspensions, there is a growing need for a seat suspension of compact construction which utilizes a seat height and weight adjustment assembly having a majority of common components for reducing cost while enabling seat height adjustment to be performed independently of weight adjustment and weight adjustment to be performed independently of height adjustment.